In the field of implement position sensing, a variety of systems have been proposed in which the movement of the implement is electrically sensed and displayed or used to perform control functions. Conventional transducers have serious deficiencies in detecting the movement of implements, owing in part to difficulties in mounting the transducers and the harsh environmental conditions to which they are exposed. Transducers used in the heavy equipment industry are particularly subject to damage from the severe work environment. Such heavy equipment work implements are typically located in relatively unprotected areas and are subject to; for example, high g-forces, wide temperature variations, dust, water, debris, etc., which can result in both electrical and mechanical failure.
One attempt to provide a sensor which is particularly suitable for the heavy equipment industry uses radio frequency (RF) signals. One such system is disclosed in U.S. Pat. No. 4,737,705 issued Apr. 12, 1988 to Bitar, et al. Bitar transmits a ramping RF signal into a coaxial resonant cavity formed by the hydraulic cylinder. When the cylinder's resonant frequency is transmitted, the signal detected by a receiving antenna reaches a peak. The resonant frequency has a one to one relationship with the cylinder's extension. Thus, by determining the cylinder's resonant frequency, the cylinder's linear extension can be determined. However, such a system is quite expensive and may not be considered to be cost effective for certain work sites.
The present invention is directed toward overcoming one or more of the problems as set forth above.